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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
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    <title>Document</title>
</head>
<body>
    <script>
    var obj = {
        name:'jack',
        age: 18,
        sex:'男'
    }

    for(var k in obj) {
        console.log(k, obj[k]);
        
    }
    console.log('name'in obj);
    console.log('sayHi' in obj);
    var arr = ['1','3','6'];
    console.log(6 in arr);
    console.log(2 in arr);
    
    
    
    
    </script>
</body>
</html>